UNSW Embryology

Week 2 Ovary

© Dr Mark Hill (2011)

Acknowledgements

Introduction

Following ovulation the remains of the ovulating follicle within the ovary has two distinct futures, depending on whether fertilization and implantation has occurred over the next two weeks. Initially pituitary leutenizing hormone (LH) maintains the follicle and stimulates initial development. If no implantation then occurs, then the follicle will form a structure that will degenerate (luteolysis) the corpus albicans.

If implantation does occur, then the follicle is stimulated by the hormone hCG released from the conceptus that reaches the ovary through the maternal blood stream. This hormone leads to the follicle forming the corpus luteum, which now acts as an endocrine organ secreting high levels progesterone. This progesterone now maintains the uterine endometrium and prevents its normal loss and menstruation.

Note that pregnancy in both the primate menstrual cycle and other mammals estrous cycle are dependent upon formation of the corpus luteum.

(More? Week 1 - Oogenesis)

Page Links: Introduction | Some Recent Findings | Corpus Luteum | Corpus Albicans | Week 2 Overview | Abnormalities | Quick Links | References | Glossary

Related Pages: Week 2 | Timeline Week 2 | Carnegie Stage 5 - 7 | Blastocyst Implantation | Sites of Implantation | Bilaminar Embryo | Early Placentation | K12 Week 2

Some Recent Findings

Ben-Ami I, Armon L, Freimann S, Strassburger D, Ron-El R, Amsterdam A. EGF-like growth factors as LH mediators in the human corpus luteum. Hum Reprod. 2009 Jan;24(1):176-84. Epub 2008 Oct 3. PMID: 18835871

"This study aims to investigate the role of epidermal growth factor-like ligands, amphiregulin (Ar) and epiregulin (Ep), in regulation of apoptosis in luteinized human granulosa cells. LH stimulation of luteinized human granulosa cells induced biosynthesis of Ar and Ep mRNA in a time-dependent manner. ...Incubation of the cells with Ar and Ep completely abolished the increase in apoptosis rate induced by serum starvation, and concomitantly caused a pronounced increase in progesterone production. Stimulation of the cells with Ar and Ep also activated the ERK and AKT signaling cascades. Finally, we demonstrated that the pro-survival effect of Ar and Ep is partially dependent on their ability to induce progesterone production."

Corpus Luteum (CL)

(Latin, corpus = body, luteum = yellow) The remains of ovarian follicle after ovulation that acts as an endocrine organ (produce progesterone and oestrogens) supporting pregnancy and preventing menstruation (loss of the endometrial lining). Formed by proliferation of both follicular granulosa cells (granulosa lutein cells) and thecal cells (theca lutein cells) after ovulation. granulosa lutein cells and theca lutein cells and produce progesterone and oestrogens.

de Graaf first observed the corpus luteum in the ovary of a cow as a yellow structure. The plural term is corpora lutea.

(Images: UWA Blue Histology)

The corpus luteum also is the location of significant angiogenesis, driven by vascular endothelial growth factor (VEGF).

The corpus luteum consists of luteinized thecal and luteinized granulosa cells.

Luteinized Granulosa Cells

• thought that prostaglandin E2 (PGE2) acts through the cAMP signalling pathway to have luteotrophic actions.
• mifepristone induces human ovarian luteinized granulosa cells to undergo apoptosis by activating caspase-3 (PMID: 18786757)
• inhibition of inhibin B production in response to hCG stimulation (PMID: 17681301)

(More? Week 1 - Oogenesis)

Corpus Albicans

(Latin, corpus = body, albicans = whitish) The histological structure formed by the degenerating corpus luteum in the ovary if implantation does not occur and the hormone hCG is not released. The white, not yellow, because of the absence of steroid hormone synthesis/accumulation.

• heparanase identified in macrophages surrounding the forming corpus albicans (PMID: 15728796)

(More? Week 1 Notes)

Week 2 Overview- Implantation and Gastrulation

• Early Development 2
• Covering Week 2 of development
  • Finish formation of the Blastocyst
  • trophoblast, embryoblast
• Implantation
  • normal, ectopic
• Changes in the Uterus
  • Early utero-placental circulation
• Formation of
  • the Bilaminar Embryo
  • the 3 chambered conceptus
  • the Trilaminar Embryo
  • the Axial Process
• Early cell division
  • Cleavage of the Zygote
  • cleavage of zygote forms 2 blastomeres
  • cleavage with no cytoplasm synthesis
  • therefore individual cell volume decreases
  • initially synchronously, then asynchronously
• Formation of the Morula
  • there are now 16-20 cells
  • at the end of the oviduct
  • ball of cells
  • slow- centre cells, larger
  • fast- peripheral cells, flattened against zona pellucida
• Formation of the Blastocyst
  • Day 5
  • zona pellucida lost
  • uterine sercetions
  • breakdown ZP
  • support blastocyst (nutrition)
  • compaction
  • central cells now compacte
  • located on a region of the wall
  • blastoceol formation
  • cavity formed by compaction
  • fluid filled blastoceol
• Blastocyst
  • Trophoblast
    • forms the placenta
    • placental membranes
  • Embryoblast
    • Inner cell mass
    • forms entire embryo
• Early cell division
• Implantation- Trophoblasts
  • Occurs at day 6-7
  • adhesion
  • adplantation
  • implantation complete by about day 9

Abnormalities

Corpus luteum hemorrhage (CLH) is a significant problem for women taking anticoagulants (for a thrombotic disorder) or women with congenital bleeding disorders. This bleeding into the corpus luteum following ovulation is generally not a problem for healthy women.

References: Corpus luteum hemorrhage in women with bleeding disorders. Hoffman R, Brenner B. Womens Health (Lond Engl). 2009 Jan;5(1):91-5. Review. PMID: 19102645

References

Reviews

• Devoto L, Fuentes A, Kohen P, Céspedes P, Palomino A, Pommer R, Muñoz A, Strauss JF 3rd. The human corpus luteum: life cycle and function in natural cycles. Fertil Steril. 2008 Sep 13. PMID: 18793774
• Rekawiecki R, Kowalik MK, Slonina D, Kotwica J. Regulation of progesterone synthesis and action in bovine corpus luteum. J Physiol Pharmacol. 2008 Dec;59 Suppl 9:75-89. Review. PMID: 19261973
• Stocco C, Telleria C, Gibori G. The molecular control of corpus luteum formation, function, and regression. Endocr Rev. 2007 Feb;28(1):117-49. Epub 2006 Oct 31. Review. PMID: 17077191
• Irving-Rodgers HF, Roger J, Luck MR, Rodgers RJ. Extracellular matrix of the corpus luteum. Semin Reprod Med. 2006 Sep;24(4):242-50. Review. PMID: 16944421
• Bachelot A, Binart N. Corpus luteum development: lessons from genetic models in mice. Curr Top Dev Biol. 2005;68:49-84. Review. PMID: 16124996

Articles

• Järvelä IY, Ruokonen A, Tekay A. Effect of rising hCG levels on the human corpus luteum during early pregnancy. Hum Reprod. 2008 Dec;23(12):2775-81. Epub 2008 Aug 10. PMID: 18694877
• Ben-Ami I, Armon L, Freimann S, Strassburger D, Ron-El R, Amsterdam A. EGF-like growth factors as LH mediators in the human corpus luteum. Hum Reprod. 2009 Jan;24(1):176-84. Epub 2008 Oct 3. PMID: 18835871
• C Chandras, T E Harris, A López Bernal, D R E Abayasekara, and A E Michael PTGER1 and PTGER2 receptors mediate regulation of progesterone synthesis and type 1 11β-hydroxysteroid dehydrogenase activity by prostaglandin E2 in human granulosa–lutein cells J Endocrinol. 2007 September; 194(3): 595–602. Prepublished online 2007 June 13. doi: 10.1677/JOE-07-0128. PMCID: PMC2040272
• Luiz E Henkes, John S Davis, and Bo R Rueda Mutant mouse models and their contribution to our knowledge of corpus luteum development, function and regression Reprod Biol Endocrinol. 2003; 1: 87. Published online 2003 November 10. doi: 10.1186/1477-7827-1-87. PMCID: PMC293426
• Lane K Christenson and Luigi Devoto Cholesterol transport and steroidogenesis by the corpus luteum Reprod Biol Endocrinol. 2003; 1: 90. Published online 2003 November 10. doi: 10.1186/1477-7827-1-90. PMCID: PMC280730

Search PubMed

Search Apr 2009 "corpus luteum" 12,846 reference articles of which 1,012 were reviews.

Search PubMed: term = corpus luteum | corpus albicans | human corpus luteum | granulosa lutein cells

Glossary

Terms

angiotensin II

anti-granulosa luteinized cells (GLCs) antibodies in infertile patients

corpora lutea - plural of corpus luteum.

corpus luteum

endocrine gland vascular endothelial growth factor (EG-VEGF) - from granulosa lutein cells, synthesis is highest during the mid- to late luteal phase.

endothelin system - influenced by endocrine and paracrine factors. granulosa lutein cells

forkhead box O1 (FOXO) - FOXO1, FOXO3, and FOXO4 are expressed in human luteinized mural granulosa cells.

heparanase (HPSE) - an enzyme (endoglycosidase) that cleaves heparan sulfate proteoglycans, major components of the basement membrane and extracellular matrix.

human chorionic gonadotrophin (hCG)

luteinizing hormone receptor (LHR)

luteinized human granulosa cells

luteolysis - degeneration of the corpus luteum

progesterone

progesterone receptors

steroidogenic cells

steroidogenic acute regulatory protein (StAR) - a protein involved in steroidogenesis

steroidogenic factor 1

theca lutein cells (thecal cells)

Quick Links

Week 2 Pages:

Introduction | Timeline Week 2 | Carnegie stages 5 to 7 | Abnormalities | Blastocyst Implantation | Sites of Implantation | Bilaminar Embryo | Embryonic Cavitites | Early Placentation | Molecular | Stem Cells | References | Text only | WWW Links | Movies - Week 2

UNSW Embryology ISBN: 978 0 7334 2609 4

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